The invention relates to a roll stand with a pair of work rolls for rolling a metal strip, comprising back-up rolls which provide lateral support to their respectively allocated work rolls, with support force directed towards the work rolls being able to be applied to said back-up rolls by means of a force generation device, and comprising support rolls or intermediate rolls which are borne by a chock, which can be slid into said roll stand in the direction of the longitudinal axis of said chock and wherein said chock can be withdrawn from the roll stand, with each support roll or intermediate roll supporting an associated work roll in a direction which is essentially perpendicular to the direction of movement of the metal strip.
In a roll stand known from DE 29 19 105 C2, each of the work rolls is supported on a support roll via an intermediate roll. At the same time, two back-up rolls are associated with each work roll, with said back-up rolls being arranged so as to rest against the respective work roll laterally at opposite sides. In the known roll stand, the support roll and the intermediate roll are held in a chock. At the same time beam-shaped support members for the back-up rolls are attached in an articulating manner. The lateral dimensions of the support member are limited to such an extent that the support members with the back-up rolls do not laterally protrude from the chock. In this way the chock constitutes a constructional unit together with the support roll, the intermediate roll and the back-up rolls as well as the associated support elements and bearing elements. For the purpose of maintenance and repair, this constructional unit can easily be withdrawn from the roll stand and subsequently can be slid back into place again. In the known device, the required back-up forces are provided by means of manually adjustable bolts which laterally impinge on the support members, without being coupled to said support members.
The known embodiment of a six-roll stand as explained above, is associated with the advantage that the constructional unit comprising the chock and the components borne by it, is of compact design. This embodiment makes it possible to change this constructional unit within a short time. However, with the known roll stand it has been shown to be difficult in practical application to quickly exchange for example a support roll or one of the back-up rolls, because this always necessitates extensive installation work.
Apart from the state of the art as explained above, from the Austrian patent specification AT 359 459 a roll stand is known which provides three back-up rolls to support the work roll. The back-up rolls themselves are laterally supported by hydrostatic bearings, with three of said bearings being arranged, regularly spaced apart, along the respective work roll. Also, hydraulic cylinders are provided to apply the required support forces.
This roll stand known from AT 359 459 is associated with the problem of disassembly of the back-up rolls as well as the problem of adjusting the support forces in line with the respective loads occurring during rolling.
In a further development of the previously explained state of the art, as known from DE 33 24 562 C2, the back-up rolls are held in an articulated manner via a support member which supports the support rolls and intermediate rolls. As is the case with the state of the art explained in the introduction, in this further development too, exchanging individual rolls is difficult and time-consuming.